Need help debugging E61 HX machine temperature/pressure.

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#1: Post by seoras »

About a month ago I bought a 2nd hand E61 espresso machine which I estimate to be 7-8 years old.
The problem with it is that the shots it is producing are just awful and the problem appears to be temperature.

It's an unusual machine in that for a single boiler (1.8L) HX it has a rotary pump.
Also it doesn't have a pressure switch.
Instead it uses a digital thermostat made by GICAR that you set the desired temp using DIP switches.

I've done just about everything I can think of to renovate it.
Cleaned out the E61 head, replaced the valves, gaskets and even the shower screen.
Ran descaling solution through the HX and head as well as the boiler and thoroughly rinsed out the whole lot so that there was no residual of the cleaning solution but also to remove all the particles it had dislodged.

I also replaced the thermocouple which is surfaced mounted on the top of the boiler.
Bought a group head pressure gauge too and it confirms a perfect 8.5-9bar at the head during shot pulling.

I've purchased an "Eric's thermometer" for the group head just to make sure of the temp hitting the basket.
That, I thought, would be the ultimate guide to helping me fix this but alas it makes no sense in what I'm reading and tasting.

If I pre-flush and pull a shot with the head thermometer reading 92-93C (198-200F) it tastes over cooked.
The best shots I've had have been under 89C (192F).
Spoke to the guy's who roast my coffee and they keep their commercial machine in their cafe at 93.4C (200F) for the espresso beans I use.

I keep lowering the boiler temp but the end effect is the boiler sitting at 0.8bar and the steam pressure almost useless for milk.
I'm new to owning an E61 and a bit disappointed to be honest.
A friend bought a very old entry level Rocket E61 (~15 years old I'd guess) which pulls amazing shots consistently.
I've no idea of temp but his pressure gauge sits around .95bar and it has plenty of steam for milk.
Every shot is perfect regardless of how badly prepared the basket is.
I know this because together we made ~70 coffees at a school fund raiser using it in the space of 2 hours!

Any suggestions on what to do next in debugging this would be greatly appreciated?!?

(Machine is a Sanremo Treviso LX manufactured mid 2012. Grinder is a Niche Zero)

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#2: Post by Bluenoser »

What does the Eric's thermometer read as the shot is progressing? Say at 5, 10, 15 & 20 seconds.. All I can guess is the thermosiphon is running so fast that maybe it is getting hotter throughout the shot.. although that sounds weird.. I have an HX but it has a restrictor and so behaves very differently than one without.

seoras (original poster)

#3: Post by seoras (original poster) » replying to Bluenoser »

I've tried at both ends of the scale with boiler temp.
ie set it high (105C) and pre-flush to cool to 93C then pull shot with ET giving a consistent ~93C.
Set to low (95C) and pre-flush to heat watching ET rise to 92/93C then pulling at that same consistent temp.

I even suspected the thermometer I was using, even though it is new and comes from Germany.
However comparing with other thermometers it appears to be calibrated correctly.

Thermosiphon stall was a top suspect however I've thoroughly cleaned the E61 mushroom and its jet holes more than once.
Replaced the metal filter mesh at the top of the mushroom as well as doing a descaling and particle flush of the HX pipes and group head.

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#4: Post by Bluenoser »

The HX machines I have, and those I've read about don't behave that way when pulling a shot. Now this depends on how quickly after you flush, you pull the shot.. Generally I flush and wait.. the temp on the thermometer should drop over some time.. mine drops 5F over 3 minutes.. but I have a restriction in the thermosiphon and so cycles slower.... then it start to climb again. I generally pull as it climbs (this is called a flush-n-wait).

From this point, the temp will spike significantly on the thermometer and then gradually drop off. So during the shot at times:

0 (idle). 5. 10. 15. 20. 25 seconds the temp might read (in F)
198F. 207. 205. 204. 203. 202

Even though the water is hot initially, the E61 group sucks up the "spike" and so the puck doesn't see that spike. But when I measured with a SCACE my actual brew water was about 3-5F below what the temp on the thermometer reads because the water cools slightly as it goes through the E61 and out the screen. (This is assuming a flush n wait) So in the example above, my brew water would be right around 199F +/- 2F.

I've not read about the temp reading on the group thermometer remaining constant throughout the extraction ..

Here's where a temp SCACE is really necessary with HX machines.. What you really need to do is to measure the brew water coming out to see if it is below or above what your group thermometer is reading.. The only thing I could think of is:
A) your E61 is being super-heated and even after flushes it stays hot and heats up the water as it travels from the group thermometer to the screen.. not sure why.. maybe idling too hot and you aren't waiting long enough after a flush?.. just a guess..
B) the brew water is fine and the bad taste is due to another issue.. but at least you've ruled out temperature.

I can't see any boiler water getting into the thermosiphon because the group thermometer would show that..

I don't have much experience with this stuff.. there are lots of others with better knowledge..

I had to buy a group thermometer and then borrow a temp SCACE to figure out how to use my new HX (PID) properly.. Really annoyed me at the time.. but once you have it figured out.. the machine becomes easy to use.. Maybe you can borrow a SCACE from someone/where.

Team HB

#5: Post by Jeff »

On my E61 HX, I found my "normal" temperature using my flush-and-wait approach wasn't "Scace temperature". It's just a number to let you know when to pull the shot.

For my specific machine (they're all different), I'd flush to 185° F for the first shot of the day and to 195° F for all the rest of the shots. That first flush needed to be longer because the group had been idling for 45 minutes to an hour and had gotten hotter than it normally would be. If I watched, I'd see the temperature drop to below 195 somewhere after the flush then wait for it to come back up. When it hit 196 in the way back up, I'd pull the shot. That was probably somewhere around 201°F measured on a Scace but it didn't matter to me. That was my normal. 192 or 194 would be cool and 198 would be hot.

If you don't rent a Scace you can figure out what your normal is for your coffees because it will be somewhere in between where it goes too sour and too bitter.

Your temperature number will probably be different if you use a flush-and-go method. I chose flush-and-wait because I could use the time to grind and prep the next basket. Neither approach is better, it's just what works for you.

seoras (original poster)

#6: Post by seoras (original poster) »

Thanks @Jeff and @Bluenoser for taking the time to share and advise, much appreciated!

This mornings coffee was excellent which is a rare occurrence but very weird in temperature.
The Eric's Thermometer on the head sat around 90C/194F until I flushed and watched it hit 97C/207F and then drop off back to 90C/194F.
Then, within about 10-20s, I loaded the portafilter and pulled the shot.
The ET read 89C/92F and dropped to 87C/189F and the shot was delicious (so my wife reported)
I turned it off and waited an hour before repeating for myself.
Same thing, same temps.
I've got that GICAR digital thermostat (it 'aint a real PID, so won't call it that) set to a boiler temp of 96C/205F.
It reads the temp from a surface mounted ring thermocouple mounted with an M4 bolt. Not ideal.
What's also weird is that the boiler sits between 0.6bar and 0.8bar which is hopeless for steaming milk.

I found a 5 year old post on these forums here which sounds a lot like the problem I'm having with the exact same machine.
So yesterday removed the expansion valve and cleaned it with descaling solution.
I was careful to photograph, and re-create, the visible threads as these spring loaded valves will be calibrated to a release pressure.
I suspect the guy who started that thread didn't and that's why he got a blow out.

That thread got me thinking about a possible thermosyphon stall/blockage.
I've already ran a clean but I focused more on the boiler internal. I just ran a quick flush through the HX.
So I warmed up the machine today and switched water source to a bowl of descaling solution and ran it into the HX.
I let it sit for just over an hour, switched on and hot, doing a flush every 15 minutes.
Then re-attaching to my water system and flushed clean. (Also took the top off the E61 mushroom to clean the filter mesh, not much there)
I noticed that the ET on the head hit 100C/213F on the last flush before switching back to clean water.
Never seen it do that so I'm hopeful that when I fire it up for tomorrow's brew I'll see different behaviour.

Team HB

#7: Post by Jeff »

Sounds like you're getting closer!

At least with my HX, changing the steam-boiler temperature changed the rebound speed, but not a lot of my "magic number". I ended up just leaving it where I had reasonable steam for the drink or two. I recall it being somewhere around 1.3 bar or so. A "saturated steam table" gives the relationship between boiler pressure and temperature. Once set, I didn't change it at all to change brew temperature.

I think my machine's EricS was around 206°F (~96° C) after warming up for 45 minutes to an hour. One of the US dealers described the idle temperature that they were seeing as "in the two-teens" (100-104° C), so somewhere between 95-105° C wouldn't surprise me.

Edit: I never tried running below 1 bar!

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seoras (original poster)

#8: Post by seoras (original poster) » replying to Jeff »

Thanks Jeff,
I should have added that I let the machine heat up for 1/2 hour before using it. I read somewhere that 20mins is minimal for E61/HX?

The previous owner had the GICAR digital thermostat set to 108C/227F which kept the boiler around 1.5-1.6bar
Easy to guess why they sold it given the state it is in and using it at that temp. Great for milk steam though!
I contacted the Sanremo NZ distributor/service centre and their technician said he set them to either 97C or 98C (207F/209F).
I might go up 2C and see what the steam is like there.

Yes, I agree, that once I've figured out the sweet spot with the ET temp I could ramp up the boiler temp and just flush to where I want it.
However I've tried this already and it didn't work. Another reason I suspect a thermosyphon problem, the water is just sitting there and not circulating.

Frustrating seeing my friends ancient (probably first generation) Rocket E61 HX just bang out beautiful shots and great steam with no need to pre-flush or do anything. Rocket has obviously earned its reputation for a good reason!

Team HB

#9: Post by Jeff »

It sounds like there's some offset in the Gicar to get it to read something like brew temperature. I've read about other machines that try to have a "PID HX" controlling brew temperature like this. It might be that they intentionally restrict the thermosiphon to keep the group from drifting up a lot. Maybe it was the Profitec 500??? I didn't follow those threads closely, but might be worth searching for "slow rebound" or similar. I don't remember if there was something that improved the behavior for those machines, but it might give you some clues for yours.

My experience has been that an E61 takes 40 minutes or more to stabilize to where I was confident of the temperate. I think a lot of manufacturers quote lower numbers. If the EricS reading is still climbing, you know it isn't stable yet.

Edit: Looks like @bluenoser might have some insight on this, having found HX-PID SCACE measurements (Profitec Pro 500)

seoras (original poster)

#10: Post by seoras (original poster) »

Jeff wrote: Edit: Looks like @bluenoser might have some insight on this, having found HX-PID SCACE measurements (Profitec Pro 500)
Fascinating! @Bluenoser's charts show a difference between a SCACE & Eric'sT that's significant enough to explain what I'm seeing.
If 87-88C (189-190F), read with Eric'sT, is the perfect temp for my machine then I'd guess a SCACE would measure around 92C/198F from those tables.
My Eric'sT might be even less accurate too and there's a larger margin of difference.

I just need to see how consistent I can get it with a higher boiler pressure and hopefully a quick rebound. I'll post results.

What a great discussion thread to reference. This is great, I'm not going mad after all. Thanks Jeff! (& Bluenoser!)